1. Field of the Invention
The present invention relates to a playback apparatus adapted to play back a content and a method of controlling a playback operation, and more particularly, to a playback apparatus having a capability of playing a content in a timer-controlled playback mode, and a method of controlling a playback operation such a playback apparatus.
2. Description of the Related Art
Audio/video contents are widely used in the form of digital data, and various apparatus for easily recording/playing digital data of audio/video contents are available. It is also very popular to play back a content read from a storage medium or a content received from a server via the Internet.
It is also popular to build a home network system using a LAN (Local Area Network) or a wireless LAN. Thus, it is desirable to provide a technique to easily transmit digital contents between devices in a home network system. In view of the above, efforts of establishing standards for procedures of connection between devices and control of contents are under way. One of such standards is UPnP (Universal Plug & Play) proposed by Microsoft Co., Ltd. of USA. The DLNA (Digital Living Network Alliance) guideline has been established based on the UPnP standard, and efforts of developing various devices according to the DLNA guideline are under way.
Some playback apparatuses have a capability of playing a content in a timer-controlled playback mode such that when a specified playback start time comes, the playback apparatus automatically wakes up from a sleep state and starts playback of the content. The time-controlled playback capability is often used as an alarm clock. For this purpose, it is desirable that the playback operation starts at the specified time in a highly reliable manner. However, the playback operation does not necessarily starts at the specified time. For example, if a storage medium in which the specified content is stored is not mounted on the playback apparatus by mistake, the playback operation does not start at the specified time.
In particular, in a case where a content received from a server via a network is played back, a rather long time is needed to assign network addresses and connect the playback apparatus to the server via the network, and thus the playback operation does not necessarily start at the specified time. Besides, there is a possibility that the server from which to receive the content is not in a normal operation when the specified playback start time has come. In this case, the playback operation does not start.
One technique to play back a content at a specified time is to monitor elapsed time and, if arrival of the specified time is detected during playback of a content stored on an optical disk, stop the playback in a normal playback mode and output an alarm sound (see, for example, Japanese Unexamined Patent Application Publication No. 2002-56659 (paragraphs to [0125], FIG. 15)).
One technique to start up an apparatus is to automatically start up the apparatus by using an automatic power-on circuit installed in a miniPC (Peripheral Components Interconnect) card mounted on the apparatus (see, for example, PCT Japanese Translation Patent Publication No. 02-073384 (page 8, FIG. 2)). In some systems, a data processing node monitors a signal on a network when the data processing node is in a sleep state. If the data processing node detects an AWAKE command, the data processing node starts awaking of a network controller (see, for example, Japanese Patent No. 3429806 (paragraphs to [0022], FIG. 2)).
In some communication system, when a client apparatus issues a request for service to a server being in a standby mode, an occurrence of a time-out is monitored on the basis of a start-up time estimated in advance (see, for example, Japanese Unexamined Patent Application Publication No. 2005-222101 (paragraphs to [0039], FIG. 5)).